WNV Dead Bird Surveillance

Evaluating 2004 and Plans for 2005

Dead Bird Surveillance Program 2000-2004

Year# Birds

Reported# Birds Tested

# Birds Positive

2000 40 20 0

2001 68 18 0

2002 3,666 653 0

2003 8,650 1,765 96

2004 92,489 5,395 3,214

Challenges and Solutions to Improve Hotline

Challenge: Increase the number of calls that can be received by hotline staff.

Solution:• The number of telephone ports was increased

from 3 to 14 in late July, but this will be increased much earlier in 2005 along with increasing the number of operators to handle live calls.

Challenges and Solutions to Improve Hotline

Solution:• We added a feature so callers will not

receive a busy signal, rather they will hear a message to call another number (the CDC hotline) or to hang-up and call again later.

932

1076

1280

1034

624

20598

31547

8092

24231

51236

0

200

400

600

800

1000

1200

1400

June July Aug Sep Oct

0

10000

20000

30000

40000

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60000

Hours Worked # Calls

Number of Calls to the Hotline vs Staff HoursN

umbe

r of H

ours

Wor

ked

by H

otlin

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aff

Num

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f Cal

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# Calls Per Day (8-1-04 to 8-7-04)

1440

2196

1092

18421748

1906

2307

0

500

1000

1500

2000

2500

Sun Mon Tues Wed Thurs Fri Sat

Day of the Week

Num

ber o

f Cal

ls

# Calls

Average # Calls Per Hour (Weeks 23 - 43)

1 1 0 0 0 17

32

101108

102

88

73 69 67 6360

46 44

35

20

8 6 4

0

20

40

60

80

100

120M

IDN

ITE

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:59a

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ON

-12:

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Hour of Day

Num

ber

of C

alls

Challenges and Solutions to Reduce Turnaround Time

Challenge: Reduce turnaround time from dead bird carcass submission to getting test results.

Challenges and Solutions to Reduce Turnaround Time

• Local agencies can do VecTest/RAMP on all corvids with no further testing required on positives (84% of carcasses last year were corvids).

• Oral swabs can be sent directly to CVEC for negative VecTest and RAMP evaluation.

• All crows should be tested either by VecTest/RAMP or by sending oral swab to CVEC (52% of carcasses last year were crows).

• Elimination of necropsy step for crows will reduce turnaround time.

Challenges and Solutions to Reduce Turnaround Time

• CVEC will make every effort to report test results on Mondays and Wednesdays, instead of just Wednesdays.

• DHS is developing a model using dead bird reports to forecast human risk.

Challenges and Solutions to Reduce Turnaround Time

• Encourage local Public Health Laboratories to do dead bird testing.- We are working with interested PH labs

to initiate RT-PCR testing or VecTests using oral swabs; CVEC will establish a proficiency panel for quality control.

• With implementation of the above items, we estimate a 61% reduction in average turnaround time (from 9.8 days to 3.8 days).

Challenges and Solutions of Positive Zip Code List

Challenge: Some local agencies were unaware that they, in fact, controlled whether zip codes were “opened” or “closed”.

Solution: • As in 2004, proposed zip code closure lists

will be sent out 24 hrs in advance of hotline notification to local agencies. We ask that the list be reviewed and agencies respond back within 24 hrs to VBDS if they do NOT want a particular zip code closed.

Issues raised by agencies in 2004Some agencies requested that federal funds be redirected to mosquito pool testing at the expense of the dead bird program.

• CDC funds were allocated to mosquito pool testing in 2004. This will continue in 2005 so agencies will not have to pay the full cost for testing.

• Mid-season supplemental funds from CDC were obtained to support the dead bird program due to the high volume of testing in 2004.

Importance of Dead Bird Surveillance Program

• The dead bird surveillance program is the only surveillance element that covers ALL 58 counties whereas mosquito pool testing is limited to only those areas with established mosquito control programs.

• There were 22 counties that had dead birds as the ONLY evidence of WNV in 2004.

Issues Raised by Agencies in 2004Some local agencies expressed that the dead bird surveillance program was simply a “data gathering tool”.

• Data gathering is the critical part of any surveillance system. The DHS goal was to provide the test results the same day we received them. We met that goal even though there were many 9:00 pm work nights.

• DHS reported the test results rapidly so that local health departments and mosquito control agencies could use the data for control and education programs.

• DHS also used the data to provide the media and general public with timely “website” information on WNV activity.

• These data were communicated biweekly to the Governor’s office and legislators upon request.

Risk Factors

Equine Cases (WEE)

EnvironmentalConditions

Rainfall

Runoff Temperature

Adult MosquitoVector Abundance

Virus Isolation Rate

ChickenSeroconversions

Human Cases

Proximity of virus activity to

populatedareas

Average

Overall Risk Level

Dead Birds

Risk Factors RatedAverage rating determined for seven risk factors and correlated with response level

Normal season 1.0 to 2.5Emergency planning 2.6 to 4.0

Epidemic 4.1 to 5.0

Dead Bird Infection

1 No WN positive dead birds in California

2 WN positive dead bird in neighboring state, but not CA

3One confirmed WN positive dead bird in CA, but none in specific region

4One confirmed WN positive dead bird reported in specific region

5Multiple confirmed WN + dead birds and multiple reports of dead birds in region

Surveillance Factor Value Benchmark

Changes in 2005

Publish dead bird reports, not just test results.

This will be done every week by county via the website www.westnile.ca.gov

Changes in 2005

Advise all local agencies of the test results for exotic birds and tree squirrels.

After evaluating this program in 2004, DHS will provide this information to all agencies in a weekly report.